Method and means for making reproductions



May 5, 1965 J. J. STONE, JR

METHOD AND MEANS FOR MAKING REPRODUCTIQNS Filed Dec. 5, 1960 INVENTOR, J e h James STFHBJI? 0 J M, M

HTi's United States Patent 3,185,999 METHOD AND MEANS FOR MAKING REPRODUCTIONS Joseph James Stone, .Ir., Glenview, Ill., assignor to A. B.

Dick Company, Niles, 11]., a corporation of Illinois Filed Dec. 5, 1960, Ser. No. 73,582 8 Claims. (Cl. 346-74) This invention relates in general to reproducing systems and, more particularly, to an image-reproducing ment is necessary or the recording paper immediately undergoes a visible change which makes the reproduced items visible. In both cases, the paper is extremely sensitive and the light exposure must be either accurately gauged or frequently changed and in addition, because of the nature of the paper in the latter case, the recording is usually not too stable, while in the former case, special developing solutions must be provided for processing the reproducing paper after its exposure. Further, the material or substance used for recording the image on the instrument is of considerable importance in determining the quantity of light and the character of the reproduction and considerably limits the versatility of most reproducing or duplicating apparatus.

The present invention is intended to avoid the aforementioned difficulties by the use of photoconductive devices for transferring images to videograph paper. In this arangement the videograph paper, together with the instrument to be reproduced or recorded, are passed over a matrix of photocondutcive devices to register the variations in conductivity of the devices as electrical charges on the videograph paper in accordance with the light and dark phases of the image to be transferred. These charges are easily rendered visible by a simple dusting process in accordance with a well-known technique used with videograph paper to provide a stable reproduction of the instrument. By simple transposition of the potentials applied to the matrix, it is possible to reproduce the image in either a light or dark chamber, or reproduce the image without regard to a specific quantity of light or the character of the substance recording the original image.

It is an object of the present invention to provide an improved duplicating arrangement for reproducing an instrument.

It is another object of this invention to provide a duplicating arrangement which is independent of the quantity of light or the character of the substance in which the original is recorded.

It is another object of this invention to provide a duplicating arrangement utilizing photoconductive cells.

It is another object of this invention to transfer an image from one instrument onto another instrument by means of discrete charged areas on said other instrument corresponding to respective areas of the first instrument.

It is another object of this invention to provide a duplicating arrangement utilizing photoconductive cells of the cadmium sulfide or selenide type. I

It is another object of this invention to provide a duplicating arrangement wherein an image on one paper is p a C transferred to another paper by means of photoconduetive cells and without regard to the overall light intensity to whichsaid cells, are exposed.

Other objects and features of this invention will become apparent on examination of the following specification, claims and drawings.

FIGURE 1 illustrates on circuit in which the respective photoconduct-ive cells are arranged to create potentials of sufiicient magnitude to charge discrete areas of a recording or reproducing paper;

FIGURE 2 illustrates a portion of a matrix arrangement in perspective to illustrate the physical displacement of the various components;

FIGURES 3 and 4 illustrate respective elevational and plan views of another matrix arrangement for transferring images; 9

FIGURE 5 is a perspective view of an original with the image thereon depicted as the letter R;

FIGURE 6 is a perspective view of the copy sheet having the latent electrostatic image on the surface thereof; and

FIGURE 7 is a perspective view of the copy sheet with the developed electrostatic image.

Referring to FIGURE 1, there Will be seen a number of photoconductive devices 10 connected between a respective Writing stylus 12 and a common lead 14. Each stylus is in turn also connected through a respective resistor 16 to another common lead 18. The photoconductive devices 10 preferably are of cadmium sulfide or cadmium selenide which have a pronounced photoconductive property, responsive to activation by light. In other words, the resistance to passage of current through the cells or devices 10 will vary, depending on the amount of light striking the cell. The potentials are applied to the respective common leads 14 and 18 so that the potential existing at each stylus 12 corresponds in value to the change in resistance offered by the respective device 10 under control of the light to which it is exposed.

In FIGURE 2 one physical arrangement 24 for supporting the matrix of photocondutcive devices 10 and resi tors 16 in an insulator block 25 is illustrated. In this arrangement, ground potential is applied to the com mon lead 14 and about 700 or 800 volts is applied to common lead 18. The lower portions of the styli 12 constitute the resistances 16. A conductor 26 extends between the upper portion of each stylus 12 and the corresponding photoconductive device 10. If the copy paper or sheet indicated at 19, together with an instrument or original 20 from which an image is to be reproduced, are passed over the photoconduct-ive devices 10 in the dark, a large proportion of the 800 volts provided at common lead 18 will exist at the writing styli 12. This voltage will vary in accordance with the light transmitted by respective portions of the instrument 20 to vary the negative charge at the Writing styli. The result is to deposit a negative charge across the respective areas of the copy paper corresponding to the image to be reproduced. Thus, as the writing styli are arranged in sufficiently closely spaced-apart relation to provide a desired number of points or lines to the inch, an electrostatic image 30, closely resembling the original 31 and with the electrostatic density corresponding to the depth of color in the original, will be transferred from the styli onto the surface of the copy sheet 19. This latent charged image 39 can then be developed by oppositely charged colored particles, pigments or smokes, to develop the image 33, as in the well-known zerographic process. The copy sheet 19 may be of the well-known type made of insulating paper or the like, and characterized by the ability to receive and hold discrete surface charges, so as to form electrostatic latent images. In the preferred practice, it is desirable to make use of an electrostatic reproduction arrangement having as many as 100 styli or lines to the inch and preferably more than 200, it being understood that the tone and the clarity of the image will increase in proportion to the number of styli per inch.

In the arrangement shown in FIGURES 3 and 4, on the other hand, the common lead 14- is connected to the high voltage, while the common lead 18 is connected to ground. In this case, each resistive element 16 is sandwiched between the common lead 18 and the corresponding writing stylus 12 with the potentials connected in a manner opposite to that described in connection with FIGURE 2. A bar 27 is provided to support the resistors 16. Light flooding the instrument 20 from which an image is to be reproduced on the copy paper 19 causes the major portion of the voltage to appear across the resistive element 16 so that a positive image is deposited on discrete areas of the paper 19 corresponding to respective portions of the image. It will be appreciated, of course, that the method of creating the image is not necessarily limited to one wherein the entire chamber is subject to one light condition, but instead a so-called flying spot of light may be used. This would be, for example, a pencil or beam of light directed in a scanning or periodic sequence over the paper to be reproduced and the cells associated with respective portions thereof. On the other hand, the reproduction from a remote position may be made by directing pencil of light at successive cells as the videograph paper is passed over the styli to modulate the voltage thereat in accordance with the image being scanned at a distant point. Thus the arrangement may be used in either facsimile or television print-out.

There has been described in the aforementioned specification several arrangements for transferring a recorded image to a reproducing paper by charging said paper in accordance with discrete areas of said image without regard to the quantity of light or the substance of the recorded image, thereby providing an improved duplicating arrangement whose concepts are more adequately set forth in the appended claims.

I claim:

1. Apparatus for duplicating an image on a sheet which is capable of recording images by means of discrete charged areas, comprising the combination of a matrix of photoconductive elements for receiving light from the image, a matrix of writing styli corresponding to said photoconductive elements for supplying variable discrete charges to the recording sheet, first and second common leads adapted to be connected to the oppositely polarized terminals of a source of high voltage, each of said photoconductive elements being connected between said first common lead and the corresponding stylus, and a plurality of resistors connected between the individual styli and said second common lead whereby the variable currents through said photoconductive elements will produce variable voltage drops across said resistors.

2. Apparatus for duplicating an image upon an insulating sheet having the character of retaining discrete charged areas, comprising the combination of a plurality of photoconductive devices for selective illumination in accordance with the image to be duplicated, a plurality of writing styli corresponding to said photoconductive devices for supplying variable discrete charges to the sheet on which the image is to be recorded, a source of high voltage having first and second oppositely polarized common leads extending therefrom, each of said photoconductive devices being connected between said first common lead and the corresponding stylus, and a plurality of resistors connected individually between each stylus and said second common lead so that variable currents through said photoconductive devices will vary the voltage drops across said resistors.

3. The apparatus of claim 2, in which said first common lead is ground and said second common lead is charged with a high voltage relative to ground.

4. The apparatus of claim 2, in which said second common lead is grounded and said first common lead is charged with a high voltage relative to ground.

5. The apparatus of claim 2, in which said first common lead is the negative terminal and said second common lead is the positive terminal.

6. The apparatus of claim 2, in which said first common lead is the positive terminal and said second common lead is the negative terminal.

7. The apparatus of claim 2, in which each of said photoconductive elements comprises cadmium sulfide.

8. The apparatus of claim 2, in which each of said photoconductive devices comprises cadmium selenide.

References Cited by the Examiner UNITED STATES PATENTS 2,432,303 12/47 Fox 346-109 2,501,790 3/50 Silverman 346-74 2,730,694 1/56 Williamson 34674 2,890,923 6/59 Huebner 34674 2,898,468 8/59 McNaney 346-74 X 2,919,171 12/59 Epstein et al 34674 3,090,828 5/63 Bain 34674 IRVING L. SRAGOW, Primary Examiner. NEWTON N. LOVEWELL, Examiner. 

1. APPARATUS FOR DIPLICATING AN IMAGE ON A SHEET WHICH IS CAPABLE OF RECORDING IMAGES BY MEANS OF DISCRETE CHARGED AREAS, COMPRISING THE COMBINATION OF A MATRIX OF PHOTOCONDUCTIVE ELEMENTS FOR RECEIVING LIGHT FROM THE IMAGE, A MATRIX OF WRITING STYLI CORRESPONDING TO SAID PHOTOCONDUCTIVE ELEMENTS FOR SUPPLYING VARIALBLE DISCRETE CHARGES TO THE RECORDING SHEET, FIRST AND SECOND COMMON LEADS ADAPTED TO BE CONNECTED TO THE OPPOSITELY POLARIZED TERMINALS OF A SOURCE OF HIGH VOLTAGE, EACH OF SAID PHOTOCONDUCTIVE ELEMENTS BEING CONNECTED BETWEEN SAID FIRST COMMON LEAD AND THE CORRESPONDING STYLUS, AND A PLURALITY OF RESISTORS CONNECTED BETWEEN THE INDIVIDULA STYLI AND SAID SECOND COMMON LEAD WHEREBY THE VARIABLE CURRENTS THROUGH SAID PHOTOCONDUCTIVE ELEMENTS WILL PRODUCE VARIABLE VOLTAGE DROPS ACROSS SAID RESISTORS. 